In most countries of the world there is a move towards adopting a coordinated cadastre and we can expect that Australia will follow this trend in the near future. Initially coordinates are being used simply as another dimension to assist in the location of parcel corners, but as control becomes more established, coordinates will become the sole definition. There are several factors which will force this change and they include the need to be compatible with all computerised information systems and the fact that it is now easier to fix absolute position by GPS than it is to measure a dimension. The regulations for the location of boundaries have always reflected the technology available at the time and there is no reason why this trend will not continue.
The Torrens system was adopted because it provided a guarantee of title, a coordinated cadastre can provide a guarantee of the land itself. There is no concept of "be it a little more or a little less", for the corner is unambiguously defined as an absolute position on the earths surface.
The strongest argument against change is that the current system works reasonably well. The level of litigation is relatively low, the cost for remarking a boundary is not excessive and people in general are not worried by boundary disputes. However, the pressures for change are quite strong and will increase as GPS becomes widely used in the community and computerised information systems become the norm in local government and other areas.
While the establishment of a coordinated cadastre may be difficult, the maintenance of such a system is relatively simple since it does not rely on a "chain of surveys ". Just as Torrens Title simplified the guarantee of ownership and greatly reduced legal costs, a coordinated cadastre will simplify the location of boundaries and reduce surveying costs. While most surveyors would not argue about the principles of a coordinated cadastre, most would have strong reservations about how to build such a system.
If we are to have an orderly transition from a metes and bounds cadastre to a coordinated cadastre it will be necessary to build the new system using existing data so that the coordinates so derived are the best that we can devise to define the actual position of boundaries on the earths surface.
It is totally impractical and unnecessary to resurvey every parcel for there is already adequate dimensional data available within the existing survey record system to carry out this job provided that control data is applied where needed.
Due to changes in the Survey Practise Regulations, geodetic coordinates are being propagated throughout the cadastral network in NSW and over the last twelve months the LTO has been evaluating procedures to use this data to improve and automate the checking of new surveys. The work has included the building of coordinated cadastre over test areas and the development of procedures to evaluate new surveys in these areas. The process of "checking and charting" new plans by the comparison of "metes and bounds" has not changed very much over the last 100 years, however the introduction of coordinates does provide an opportunity for a complete review.
The cadastral framework for an area is built up progressively using all available information which is then evaluated and used to compute coordinates for all parcel corners. The aim is to derive the position on the earths surface for the actual parcel corner. First, all existing documentary data is entered using a specialised spreadsheet system, then groups of about 300 parcels are joined together using a mouse and "on screen graphics" to select common points etc.
Each group is then adjusted to geodetic control points using a "least squares" adjustment program which automatically weights each survey according to its date and the survey practise regulations in force at that time. As sections are completed they are stored in a master data base so that the digital cadastre is progressively assembled and refined. This system was originally developed by the University of Newcastle about five years ago as part of a research project which was funded and supported by the LIC and the Computer Users Group of the Consulting Surveyors Association. It has been progressively refined over the last five years by MIMAKA and has been used to process more than 15,000 parcels of land. This data includes areas from most states in Australia as well as Malaysia, the Philippines and New Zealand.
The Northern Territory has adopted the process to effect the transition from their existing "metes and bounds" cadastre to a coordinated system. They are using both "in house" staff to process the work as well as letting whole areas to contract. Because of the checks built into the system it is relatively easy to ensure the quality of the contract work with minimal supervision and the surveying profession provides a very skilled workforce experienced in working with cadastral data.
There is no doubt that a coordinated cadastre will replace the current system and that as a consequence boundary definition as we know it will disappear. Already most new subdivisions are calculated and set out using coordinate data. These areas could already be considered as a "coordinated cadastre" and redefinition be remarked by using GPS only. The main problem is in converting existing data so that the integrity of the current system is maintained.